As somebody already pointed out, the original PC version didn't have scores either. We did cover the topic when we started creating the iPhone version, but since the game worked well without the scores already and it seemed that only a very few people were missing the scores, we didn't want to change that. Simply, we've never seen Sparkle as a "highscore game".

We've implemented online leaderboards for some of our games which have a heavily score based gameplay like Boom Brigade, Rope Raider, and Belowscape.

As for OpenFeint and other similar services, we've considered those too but haven't actually used them yet. It would be really awesome if there was a solid multiplatform social gaming service that would work on iPhone, PC, Mac, Android, and more. Many services are really iPhone centered but we'd like to deliver games for all suitable platforms. The iPhone is probably the most influential mobile gaming platform at the moment, so this isn't too surprising, but there are other platforms too. Scoreloop has support for iPhone and Android and I think OpenFeint will also support Android. Hopefully they'll add official PC and Mac support as well.

If there was a simple to use white-label (meaning that we could do our own game-specific user interface for all highscore functionality) multiplatform social gaming service, we would definitely consider it. Let us know if there is one! However, this is not to say that we won't pick up OpenFeint or some another service at some point - Just passing some thoughts about the topic.